Homemade Masks In A Time Of Shortage

March 18, 2020 by Sharon Lin 528 Comments

Due to the worldwide pandemic of COVID-19, there has been a huge shortage of ~~N95~~ masks. [Paddy Robertson] from Smart Air has been working on designs for a DIY mask that may be able to protect those who haven’t been able to secure their own masks. While there may be an abundance of memes around the various material people have been able to use to substitute for the filters, there is some very real science behind the sorts of materials that can effectively protect us from the virus.

According to a studied performed at Cambridge University during the 2009 H1N1 flu pandemic, while surgical masks perform the best at capturing Bacillus atrophaeus bacteria (0.93-1.25 microns) and Bacteriophage MS virus (0.023 microns), vacuum cleaner bags, and tea towels~~, and cotton T-shirts~~ were not too far behind. The coronavirus is 0.1-0.2 microns, well within the range for the results of the tests.

As it turns out, cotton homemade masks may be quite effective as alternatives – not to mention reusable. They also found out that double layering the masks didn’t help with improving the protection against viruses. On the other hand, one significant design choice was the breathability of the material. While vacuum cleaner bags may be quite effective at keeping out small particles, they aren’t as comfortable or easy to breathe in as cotton masks.

Have you tried making your own cotton masks? In a time when hospitals are running low on surgical masks, it’s possibly the best option for helping to keep much-needed medical supplies in the hands of those helping at the front line.

[Thanks to pie for the tip!]

Hearing Plants Giggle Is Just As Creepy As You Think

March 18, 2020 by Tom Nardi 13 Comments

While best known for Charlie and the Chocolate Factory, Roald Dahl wrote quite a few similarly oddball stories in his time. One of them, The Sound Machine, is about a device that allowed the user to hear the anguished screams of trees as they were cut down. Sounds kind of weird to us, but [Roni Bandini] liked the idea so much he decided to build his own version.

Now to be fair, the device doesn’t only scream in pain. In fact, most of the time it should be emitting laughs and happy noises. Using a moisture sensor driven into the soil of a plant’s pot, the device uses these audio cues to tell you the relative health of your leafy friend. So assuming you’ve got any sort of green thumb at all, things should be fine.

But once the soil gets too dry and the device determines the plant is in “pain”, things take a turn for the worse. We suppose it doesn’t technically scream out so much as grunt like a zombie, but it’s still not a noise we’d want to hear while walking through the house at night. Luckily, it seems you need to hit the button on the front of the 3D printed enclosure to get it to play the appropriate sound track from its DFPlayer module.

Personally we’d rather build something that makes sure the plants are being taken care of automatically than a gadget that cries out in anguish to remind us that we don’t know what we’re doing. But hey, everyone gets inspired in their own way.

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John Deere And Nebraska’s Right To Repair, The Aftermath Of A Failed Piece Of Legislation

March 9, 2020 by Jenny List 99 Comments

For the past few years now we’ve covered a long-running battle between American farmers and the manufacturers of their farm machinery, over their right to repair, with particular focus on the agricultural giant John Deere. The manufacturer of the familiar green and yellow machinery that lies in the heart and soul of American farming has attracted criticism for using restrictive DRM and closed-source embedded software to lock down the repair of its products into the hands of its dealer network.

This has been a hot-button issue in our community as it has with the farmers for years, but it’s failed to receive much traction in the wider world. It’s very encouraging then to see some mainstream coverage from Bloomberg Businessweek on the subject, in which they follow the latest in the saga of the Nebraska farmers’ quest for a right to repair bill. Particularly handy for readers wishing to digest it while doing something else, they’ve also recorded it as an easy-to-listen podcast.

We last visited the Nebraska farmers a couple of years ago when they were working towards the bill reaching their legislature. The Bloomberg piece brings the saga up to date, with the Nebraska Farm Bureau failing to advance it, and the consequent anger from the farmers themselves. It’s interesting in its laying bare the arguments of the manufacturer, also for its looking at the hidden aspect of the value of the data collected by these connected machines.

It’s likely that the wider hardware hacker community and the farming community have different outlooks on many fronts, but in our shared readiness to dive in and fix things and now in our concern over right to repair we have a common purpose. Watching these stories at a distance, from the agricultural heartland of the European country where this is being written, it’s striking how much the farmers featured are the quintessential salt-of-the-earth Americans representing what much of America still likes to believe that it is at heart. If a company such as John Deere has lost those guys, something really must have gone wrong in the world of green and yellow machinery.

Header image: Nheyob / CC BY-SA 4.0

Generate Power As You Ride With A Bicycle Planar Alternator

March 2, 2020 by Jenny List 21 Comments

For most riders, bicycle lighting consists of an array of LED lamps and flashing gizmos, usually powered by lithium-ion batteries, or coin cells for the smaller ones. Some people though prefer to dispense with batteries and generate their own power, and that’s what [Thomas D] has done by fitting his bike with an alternator. But this is no off the shelf unit that rubs the tire or sits in a wheel hub. Instead, he’s built his own planar alternator that attaches to the spokes.

The design is inspired by those used in some wind generators, a central disk holding a set of planar coils sits between two rotating disks holding magnets. The stator holding the coils is made from laser-cut acrylic, and the rotors holding the magnets are sheet steel. One rotor is attached to the rear wheel spokes of the bicycle in close proximity to the stator which is attached to the rear frame. The second rotor sits on the other side of the stator while attached to the first rotor by its edge.

The coils are wired as two parallel groups in series in a ring with a single-phase output that feeds a rectifier and DC to DC converter. It would be interesting to see the effect of the same alternator with different winding arrangements or multiple phases.

This is the first time we’ve seen one of these on a bicycle, but this type of alternator has appeared here in more than one wind generator.

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Make A Vintage-Looking Clock In A Flash

February 23, 2020 by Kristina Panos 8 Comments

Now that everyone has a phone with a camera, we would bet that fewer people than ever are in the market for a nice vintage flash unit such as the one [lonesoulsurfer] chose for this cool clock build. But here’s something that never goes out of style — a clock that doubles as a conversation piece.

At the heart of this build is a dirt cheap clock unit meant for cars. It also displays the ambient temperature and has a voltage testing mode(!), which could come in handy someday. Although [lonesoulsurfer] didn’t connect a pair of probes, he did cut a wee hole for the temperature sensor to stick out of. He also cut off the SMD buttons and wired new momentaries to the outside of the case.

Although we really like the look of the textured plastic lens over the 7-segments, our favorite part might be the stand and the way [lonesoulsurfer] implemented it. He made a threaded rod by pounding a hex nut into the end of a piece of aluminium tubing, and then dropped a bolt through the bottom of the flash body before closing it up, so it screws on like a camera to a tripod. Take a second and check out the build video after the break.

We love a good clock so much that we just had a contest to find the coolest ways to tell time. In case you missed it, here are the best of the best.

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Airport Split-Flap Letters Carry On As Spotify Display

February 11, 2020 by Kristina Panos 25 Comments

Today’s tale of being in the right place at the right time comes from [fabe1999], who was doing an intern gig at the airport when the controller on their split-flap display bought a one-way ticket going south. They were just going to throw away thousands of these letters and replace them with monitors, but the intern intervened.

[fabe1999] grabbed an armload, took them home, and set about making them flap again, one letter at a time. An ATtiny worked okay, but it wasn’t really fast enough to flip them at their full clacking potential, so [fabe1999] switched to an ESP8266. So now there is one ESP for each of the 20 characters, and another that runs a web server where text can be directly entered for immediate display.

Each letter uses two sensors to flap to the right letter. The first one acts as a start sensor, detecting the blackness of a blank character. Another sensor counts the letters and makes the ESP stop the motor on the right one. So far, [fabe1999] hasn’t figured out how to recognize when a blank character can stay blank, so they flap all the way around back to blank for now. It certainly adds to the rich, flappy sound, but that can’t be good for the long-term life of the letters. Your flight is now departing for Post Break Island, where the letters are spending part of their retirement showing song titles from Spotify.

No chance of split flaps falling into your lap? Here’s a tip: you can fab your own flip.

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Hoverboard Grows Up, Becomes Magnetic Drill Press

February 4, 2020 by Kristina Panos 11 Comments

If you need to drill metal in tight places, the magnetic drill press, or mag drill is your BFF. The idea here is that a drill press with an electromagnetic base can go anywhere, and even drill horizontally if need be. If you don’t need to use one often, but want one anyway, why not build one out of e-waste?

[DIY KING 00] built this mag drill starting with the motor from a hoverboard. While these three-phase brushless motors have a lot of torque to offer reuse projects like this, they’re not designed to be particularly fast.

He was able to make it about three times faster by cutting the windings apart and reconnecting them in parallel instead of series. He designed a simple PCB to neatly tie all the connections back together and added an electronic speed control (ESC) from an R/C car.

Reluctant to give up the crown, he made his own three-coil electromagnetic base, using a drill to wind magnet wire around temporary chuck-able cores. The coils are then potted in epoxy to keep out dust and drilling debris. Everything runs from two large LiPo batteries, and he can get about 15 minutes of high-torque drilling done before they’re dead. Can you feel the electromagnet pulling you past the break to check out the build and demo video?

Depending on what you’re doing, you might get away with a magnetic vise instead.

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